#! bin/bash

grep -v -E 'b|B' text3.txt
grep -iv "b"
grep -v '[bB]'


cat text3.txt | grep -v -E 'b|B'
cat text3.txt | grep -vi "b"

awk '$0!~/b|B/ {print $0}' text3.txt
awk '!/[bB]/'

sed '/[Bb]/d'
sed '/b\|B/d'
